If your point is that one of the major problems he faces is people's attitudes and inabilities to accept difference, I agree. Unfortunately we live in a world where such differences are not accepted, and a kid such as Alex, who is very different, gets beaten up, ostracised, and retreats into his own room as a place of safety. And - even if we did live in a world in which people didn't make crass and judgemental assessments based on zilch knowledge, he might well still find a lot of situations inordinately stressful, because the world is run on unspoken social rules and cues that most of us learn by osmosis, and people with Aspergers are in my experience more or less blind to. You could be an intelligent, kind, decent kid, as this one sounds, and be surrounded by other equally decent kids, and still find them completely confusing and bewildering and overwhelming as a group. And yes, I'd call that a disability, personally. I'd call being a five year old who, when told to get undressed for PE and then go to the hall, strips off, goes in naked, and finds everyone's laughing at him and he's in serious trouble disablingly stressful. And the sheer confusion of living in a world where everyone else speaks some sort of telepathic language you just don't share would be hard and bewildering and exhausting, especially when a lot of the things you find necessary or reasonable or unavoidable (watching the TV sound card; waking your sibling at 5 am because you don't appreciate the need to sleep more, aren't tired, and are climbing the walls with boredom) get you yelled at. And it's a life sentence, because even with professional help with social skills, you'll never be fluent and it'll never come instinctively.
Diabilities can be obvious to outside observers - my brother is progressively deafer as he ages, and the hearing is undeniably a "disability" to most hearing people. But you know, many in the deaf community regard it as different but equal; they regard sign language as a skill that hearing people lack. They pity our failure to comprehend the beauty of signed poetry, or to join in conversations in deaf-frequented pubs. My brother is actually not regarded as deaf by that community as he has some hearing - but he's regarded as deaf by the hearing community. tbh I think that failure to be able to identify as one or the other is in some ways harder than the disability itself. And deafness is never as hard for him as the Aspergers, because people understand, accept and work round his hearing. They are far hastier in assuming that his social difficulties are down to being boorish, or rude, or self-absorbed - and he isn't, actually, any of those things. He is inordinately kind on a practical level, he longs for the sort of easy social connections many of us take for granted, and he most of all wants a wife and kids, which are probably not going to happen for him, though (very belated) social skills assistance and the general increase in tolerance people seem to achieve in their late thirties does mean he is now tentatively acquiring some friends outside the family. You'd probably just see him as a socially awkward deaf person, who lives independently, more or less, and holds down a decent job. But that is to underestimate the huge additional effort every single social interaction exacts, and the constant extra vigilance required just to try to behave in a way that isn't seen as odd, or inappropriate, for reasons that are actually, when you break it down, pretty silly. It's to ignore that he works in IT, in the public sector, in a job that involves travelling to sites to sort out their IT, and not day-to-day office politics, because any other kind of job would pose enormous problems for him - and it's to ignore that he has been seriously discriminated against at work, too. (Told not to apply for a job because he was overqualified, despite that job being substantially better paid. Told not to apply for another as it was beyond his skill-set, then instructed to train the successful candidate. Pretty blatant, I'd say, and his most recent boss got him a several thousand pound raise after arriving and realising he was grossly exploited - and that in the supposedly transparent public sector.) That is a disability, and the fact that so many people manage to live rewarding and worthwhile lives is a testament to them as people, I think, rather than there being no disability involved.